Method and apparatus for conversion of fluid hydrocarbons



Jan. 4, 1949. H. K. HOLM v 2,458,165

METHOD AND APPARATUS FOR CONVERSION OF FLUID HYDROCARBONS Filed March18, 1947 4 Sheets-Sheet l HOPPER O INVENTOR.

HfFBERT KHOLM Maw A GENT 0 AYTOFNEY.

Jan. 4, 1949. H. K. HOLM 2,458,165

' METHOD AND APPARATUS FOR CONVERSION OF FLUID HYDROCARBONS Filed March18, 1947 4 Sheets-Sheet 2 INVENTOR.

HERBERT K HOZM.

JAMQW AGENT 0i? ATTORNE).

Jan. 4, 1949. H. K. HOLM 2,458,165

METHOD AND APPARATUS FOR CONVERSION OF FLUID HYDROCARBONS Filed March18, 1947 4 Sheets-Sheet 3 INVENTOR. HERBERT r HOLM 9M am l- AGENT 0RATTORNEY Patented Jan. 4, 1949 METHOD AND APPARATUS FOR CONVER- SION OFFLUID HYDROCARBONS Herbert K. Holm, Chicago, Ill., assignor to Socony-Vacuum Oil Company, Incorporated, a corporation of New York ApplicationMarch 18, 1947, Serial No. 735,326

14 Claims. 1

This invention has to do with a method and apparatus for conversion offluid hydrocarbons in the presence of a particle-form solid contactmaterial which may or may not be catalytic in nature.

Exemplary of the processes to which this invention may be applied arethe catalytic cracking conversion of high boiling fluid hydrocarbons,the catalytic hydrogenation, dehydrogenation, aromatization,polymerization, alkylation, isomerization, reforming, treating ordesulphurizing of selected hydrocarbon fractions. Also exemplary are thethermal cracking, viscosity breaking and coking of hydrocarbon fractionsin the presence of heated inert, solid materials.

Typical of such processes is the catalytic cracking conversion ofhydrocarbons, it being well known that high boiling fluid hydrocarbonsmay be converted to lower boiling gaseous, gasoline containinghydrocarbon products by exposure to a suitable adsorbent type catalyticmaterial at temperatures of the order of about 800 F. and higher and atpressures usually above atmospheric. Sucha process has recently beendeveloped commercially into a continuous cyclic process wherein thesolid catalyst is passed cyclically through a conversion zone wherein itis contacted with fluid hydrocarbons to eilect the conversion thereofand through a regeneration zone wherein it is contacted with acombustion supporting gas such as air which acts to burn ofi from thecatalyst a carbonaceous contaminant deposited thereon in the conversionZone.

This invention is particularly concerned with such cyclic conversionprocesses or gas-solid connature of natural or treated clays, bauxite,inert carriers upon which catalytic materials such as metallic oxid'eshave been deposited or certain synthetic associations of silica, aluminaor silica and alumina to which small amounts of. other materials such asmetallic oxides may be added for special purposes. In processes whereinthe contact material is not catalytic in nature its purpose is usuallythat of a heat carrier and may take any of a number of forms, forexample, spheres or particles of metals, stones or refractory materialssuch as mullite, zirkite, or corhart material. In order to permitpractical rates of gas flow through the contact material which ismaintained as a substantially compact column in the conversion zone, thecontact material should be made up of particles falling within the sizerange of about .005 to 1 inch in diameter and preferably .03 to 0.5 inchin diameter.

In such processes wherein the direction of gas flow through the reactionzone is countercurrent to the downward flow of the contact material, themaximum rate of gas flow should be limited to that which will not causeboiling of the contact material or serious interference with its flowotherwise serious difllculties arise such as channeling of the solid andgas flow and excessive attrition of the solid material. In manyprocesses such as, for example, the conversion of liquid hydrocarbons tolower boiling gaseous products it is desirable to pass the reactantfluid downwardly through the conversion zone concurrently with thecontact material flow. In such processes a serious difliculty arises inthe withdrawal of gaseous reactants from the contact material columnwithin the conversion zone. In one form of operation practicedheretofore a row of inverted, spaced, collecting troughs was positionedin the column of contact material within the lower section of thereactor and gas was withdrawn through suitable pipes extending under theends of the troughs. Such an arrangement is unsatisfactory due toserious entrainment of contact material in the gaseous streams withdrawnfrom'the ends of the collecting troughs.

A major object of this invention is the pro- ViSlOl in a process whereina gaseous material is contacted with a substantially compact column ofparticle-form contact material of an improved method and apparatus forwithdrawal of gas from said column without substantial entrainment ofcontact material particles.

Another object of this invention is the provision of an improved methodand apparatus for conversion of a high boiling fluid hydrocarbon to alower boiling gaseous hydrocarbon product in a confined zone in thepresence of a substantially compact column of contact material particlesflowing downwardly through said zone in the direction ofrthe reactantflow.

A specific object is the provision in a hydrocarbon conversion processwherein the contact material moves downwardly as a substantially compactcolumn of solid particles concurrently to the fluid reactant flow of apractical method and apparatus for withdrawal of gaseous conversionproducts from said column in the conversion zone without substantialentrainment of contact material particles in the eilluent gas stream.

These and other objects of this invention will become apparent from thefollowing detailed description of the invention. Before proceeding withthe description, certain expressions employed herein in describing andin claiming this invention will be defined. The term gaseous" as usedherein, unless specifically otherwise modifled, is intended broadly tocover material existing in the gaseous phase under the particularoperating conditions involved regardless of what may be the normal phaseof that material under ordinary atmospheric conditions. The expressioncontact material, unless otherwise specifically modified, is used hereinin a broad sense to cover any solid material having suitable heatcarrying and stability properties for the particular process applicationin which it is employed, and the expression is intended to broadly covercatalytic and non-catalytic materials.

The invention may be most readily understood by reference to thedrawings attached hereto of which Figure l is an elevational view of anarrangement of a cyclic conversion system to which this invention isapplied, Figure 2 is an elevational view, partially in section, of aconversion vessel constructed according to this invention, Figure 3 is avertical view, in section, of a modifled form of gas collecting trough,Figure 4 is a similar view of still another modified form of gascollecting trough. Figure 5 is an isometric view showing the stackingarrangement of troughs shown in Figure 2, and Figure 6 is a a graphicalrepresentation of certain pressure drop data obtained in connection withthe apparatus of Figure 2. All of these drawings are highly diagrammaticin form.

Turning now to Figure 1 there is shown a conversion vessel [0, aregeneration or reviviflcation vessel II and conveyors l2 and i3 fortransfer of contact material between the conversion and regenerationvessels. In operation particle-form contact material is supplied fromhopper 40 through gravity feed leg 4| into the upper section of theconversion vessel [0. Used contact material is withdrawn from the lowerend of vessel l0 through drain conduit I4. The rate of contact materialflow is controlled by valve ii on conduit i4 so that a substantiallycompact column of contact material is maintained within the conversionzone. The hydrocarbon charge tovessel i0 may exist in the gaseous phaseor liquid phase or both. The charge may be heated and completely orpartially vaporized in a suitable charge preparation system [6 which maybe of conventional design. Heated charge vapors may be admitted to theupper section of the conversion zone through conduit l1 and heatedliquid charge may be admitted through conduit l8. Gaseous conversionproducts are withdrawn, separately of the contact material, from thelower section of the conversion zone through conduit is through which itpasses to a conventional product recovery system 211. An inert seal gas,such as steam or flue gas may be admitted through conduit 2| into asealzone maintained at the upper end of vessel ill for the purpose ofpreventing hydrocarbon escape through the gravity feed leg. The rate ofseal gas introduction may be so controlled by means of diaphragmactuated valve 22 and differential pressure control instrument 23 as tomaintain a seal gas pressure in the seal zone slightly-above thehydrocarbon pressure in the upper section of the conversion zone. Aninert purge gas such as steam or flue gas may be introduced into thecontact material column below the level of gaseous reactant outlet l3through conduit 24 for the purpose of purging gaseous reaction productsfrom the outflowing used contact material. The used contact material istransferred to conveyor l2, which may be a continuous bucket elevatorfor example, to the upper end of regeneration vessel H. The regenerationvessel shown is of the multistage type, well adapted for theregeneration of spent cracking catalysts. Air or oxygen containing gasis introduced from manifold 25 into several superposed burning stagesthrough inlet conduits 26, 21 and 23. Flue gas may be withdrawn fromthese stages through conduits 23, 30 and 3l all connecting into outletmanifold 32. The contact material temperature may be controlled bypassing a suitable cooling fluid through cooling tubes located in vessell I between the burning stages. Cooling fluid may be introduced into thecooling tubes (not shown) through communicating inlets 33 and 34 andwithdrawn therefrom through communicating outlets 35 and 38. Regeneratedcontact material is withdrawn from vessel ll through drain conduit 31through which it passes to conveyor |3. The hot regenerated contactmaterial is transferred by conveyor l3 to reactor supply hopper 4|).While the regenerator described hereinabove is of the multistage type,it will be understood that other types of regenerators adapted forregenerating contact materials may be employed within the scope of thisinvention. The type of regenerator or reviviflcation vessel to beemployed will vary depending upon the particular process involved. Anyapparatus adapted to condition the contact material to a statesatisfactory for re-use in the particular conversion process involved iscontemplated to be within the scope of this invention. It should befurther understood that this invention is not considered as limited toany particular positional arrangement of conversion and regenerationvessels or to the particular apparatus described .hereinabove forcontact material introduction into the conversion vessel.

The improvement of this invention as applied to the conversion vesselIII is shown in Figure 2, wherein I0 is the conversion vessel havingsolid inlet 40 at its upper end and outlet I4 at its lower end. Apartition 43 is positioned across the upper section of the vessel Ill toprovide a seal chamber 44 in the upper end of vessel It. Contactmaterial passes from seal chamber 44 onto the surface ofthe contactmaterial column 45 in the conversion chamber therebelow throughuniformly distribuated tubes 46 which depend from partition 43. Thepartition 43 and tubes 46 combine to provide a gas distribution space 41above the contact material column in the conversion chamber. vaporizedhydrocarbons may be introduced into the gas space through conduit l1.Liquid hydrocarbons enter through conduit l3 which extends across thevessel and is closed on its end within the vessel. A number of branchpipes such as 48 and 49 may connect into the conduit it! within column45. Contact material is withdrawn from the bottom of the conversion zonethrough a.

number of uniformly distributed tubes 55 depending from a horizontalpartition 54. The streams from tubes 55 are proportionately combinedinto a smaller number of streams flowing through orifices 56 in stillanother partition within the lower section of vessel l and the streamsfrom orifices 56 are proportionately combined into a single dischargestream flowing from the conversion vessel in conduit 14. It will benoted that the orifices in partition 51 and the tubes in partition 54are arranged in circular rows and that the number of orifices withinpartition 5,! is less than the number of tubes depending from partition54 and that the orifices 56 are horizontally staggered with respect tothe tubes 55. By the gradual proportionate combination of streams into asingle discharge stream as described hereinabove uniform withdrawal ofcontact material from all portions of the cross-sectional area of theconversion vessel is insured. The number of rows of partitions withorifices or depending tubes employed depends, of course, on thehorizontal cross-sectional area of the vessel involved. While forvessels of circular cross-sectional shape, the tubes in each partitionmay be conveniently arranged as concentric circular rows of tubes. Onthe other hand, for a vessel of rectangular cross-sectional shape thetubes in each partition may be conveniently arranged spaced apartparallel rows of tubes extending across the vessel.

Within the lower section of vessel It! there is positioned anarrangement of baflles which comprises a vertical series of superimposedlayers of inverted troughs which in Figure 2 are in the shape of angleirons 60 placed one above the other in a criss-cross manner. irons 60 inany given layer are spaced horizontally apart and extend in parallelhorizontally across the vessel in a direction transverse to those angleirons in adjoining layers. Along the heel of each angle iron there areprovided a series of orifices 6| so positioned that in any angle ironthe orifices are covered by angle irons crossing thereabove. It has beenfound preferable for the orifices to be so arranged that in any angleiron the orifices are below the closed part of the angle iron crossingthereabove, rather than directly below an orifice in the angle ironabove. In order to prevent leakage of solid particles through the edgeof the orifices in the angle irons 60, it has been found desirable toconstruct the orifices in the form of small chimneys as shown inFigure 1. These chimneys may extend a short distance above the heel ofthe angle iron if desired. It will be noted that the size of theorifices 6! increase in stepwise fashion for the successive layers ofangle irons in a downward direction. The two lowermost layers of angleirons are provided along their bases with vertical skirts 63. All angleirons are provided with end plates 64 to prevent entrance of solid paticles under the ends of the angle irons.

While the form shown in Figure 2 is a preferred form of the inventionfiat topped inverted channels such as trough 80 in Figure 3 may besubstituted for angle iron 60. In the case of fiat topped channelssimple orifices 8| may be provided instead of the chimney-type orifices6| of Figure 2. A preferred form of trough construction is shown Theangle 6 thereof than on the other layers of troughs. It should beunderstood that the term trough as employed herein in describing andclaiming this invention is employed in a broad sense as covering bothangle irons of the type shown in Figure 2 and trough constructions suchas are shown in Figures 3 and 4 and troughs of other practicalcross-sectional shapes. It should also be understood that the termorifices is used herein in in Figure 4 wherein is shown a sectional viewof a gable-roofed trough 82 which may be substituted for angle irons 60.A series of chimneytype orifices such as 83 are provided along thegable-roof of trough 82. When such troughs are employed it is desirableto provide deeper vertical skirts on the troughs of the two lowermostlayers a generic sense as covering simple holes such as at 8| in Figure3 or the chimney-type of orifice shown at 6| and at 83 in Figures 2 and4 respectively.

In Figure there is shown an isometric view of two layers of stackedangle irons such as are shown in the apparatus of Figure 2. Likeelements in Figures 2 and 5 bear, like numerals.

Turning again to Figure 2, there is provided above the top layer oforifice containing angle iron troughs a layer of similar angle irons 82in which no orifices are provided. The angle irons 62 serve to preventflow of solid particles through the orifices in the layer of angle ironscovered by angle-iron 62.

Below the lowermost layer of angle irons 60 there is provided a row ofspaced gable-roofed troughs 65 running across the vessel transverse tothe angle irons immediately thereabove. Chimney-type orifices 66 areprovided in the gable roofs of troughs 65 to communicate them with thelowermost layer of angle irons. The orifices 66 are as large as orpreferably larger than those in the lowermost layer of angle irons.

Flanged nozzles 61 are provided along the vessel shell adjacent oppositeends of the troughs 65. Flanged sleeves 68 of approximatel the sameshape as troughs 65 are provided to slide through nozzles 61 and underthe opposite ends of troughs 65. The sleeves are connected to nozzles 61by flanges 69 so that they serve both as supports for troughs 65 and aspassages for flow of gas from under the troughs 65 out into the headerboxes 10 which enclose the nozzles 61 and open sleeves 68. Gas outletconduits H are connected into header boxes ID.

The above described arrangement is such that there is provided in thelower section of the vessel ID a substantially continuous tortuoussolid-particle-free gas flow passage which is in gas flow communicationwith the contact material column at a series of vertical levels andwhich is in gas flow communication with gas outlet conduits positionedoutside of vessel I0,

In operation of the apparatus shown in Figure 2 contact material entersthe seal chamber 44 through conduit 48 and passes from the bottom of theseal chamber through tubes 46 onto the surface of the contact materialcolumn in the conversion chamber. The contact material fiows downwardlythrough the conversion chamber as a substantially compact column ofgravitating particles and passes through tubes in partition 54 andorifices 56 in partition 51 to the drain conduit l4. The rate of solidflow is temperature conditions to gaseous hydrocarbon The hydrocarbonreactant is converted under suitable 7 products as it passes downwardlythrough the conversion chamber. The gaseous conversion products uponreaching the uppermost layer of angle irons tend to become disengagedfrom the solid column at surfaces formed by the normal angle of reposeof the solid material under the angle irons. A small portion of thegaseous products become disengaged at the disengaging surfaces under theangle irons 62 and then pass into the gas space provided by these angleirons.

.The remainder of the gaseous products pass downwardly through the solidcolumn between the spaced angle irons, a portion of the gas beingdisengaged from the column and collected under the angle irons at eachrow thereof. The gas collected under any given row of angle irons passesdownwardly through the chimney-type orifices in the angle ironstherebelow to Join the gas collected under the latter angle irons. Thusthe gas collected under all rows of angle irons is gradually combined sothat the stream of gas passing from the lowermost row of angle ironsthrough orifices 66 to the outlet troughs 65 comprises most of thegaseous hydrocarbon product except for a small amount of gas whichpasses down through the column between troughs 65 and is collected undertroughs 65. The total gaseous product collected under the angle ironsthen passes through sleeves 68 to manifold boxes 10 from which it iswithdrawn through conduits H.

An inert purge gas such as steam or line gas may be introduced throu hconduit 24 to the space below partition 54. The purge gas passesupwardly through tubes 55 and the bed of contact material betweenpartition 54 and troughs 65 and is finally collected under troughs 65along with the gaseous hydrocarbon product. An inert seal gas such assteam or fiue gas may be introduced through conduit 2| into seal zone 44at a rate sufficient to maintain a higher gaseous pressure in zone 44than in the space 41 of the conversion chamber. In this manner escape ofgaseous hydrocarbons through the contact material feed leg is prevented.

By the above described method and apparatus there is provided in thelower section of the conversion vessel a total amount of gas-soliddisengaging surface area which is far in excess of the horizontalcross-sectional area of the column of contact material above thebafiling. It is therefore possible by the described method to passgasdownwardly through the column in the conversion zone at a rate whichwould be suflicient to entrain the contact material and interrupt thesolid column flow, if the gas flow were upward, and still effect anupward disengagement of gas from the solid column in the lower sectionof the conversion zone without sub-tantial entrainment of solidparticles and without interruption of the solid column fiow. In order toaccomplish the proper gas-solid disengagement and in order to prevent"boiling of the contact material column and particle entrainment underthe uppermost rows of angle iron it is of great importance that thedisengaging conditions be maintained substantially uniformunder all theangle irons in all the vertically spaced layers thereof. It has beenfound that this result may be accomplished by proper proportioning ofthe size of the orifices in the successive rows or layers of angleirons. Broadly speaking this has been found to involve the provision oforifices in the angle irons which increase in size in a stepwise fashionfor successive layers of angle irons in a downward direction. The sizeof the orifices in the uppermost layer of angle irons containingorifices should be such as to cause a pressure drop due to the downwardflow therethrough of the amount of gas collected under angle irons 52 ofthe uppermost layer, which pressure drop is equal to that caused by theflow of the residual gas not collected under the uppermost layer ofangle irons through that vertical portion of the solid column lyingbetween the base of angle irons 62 and the base of the angle irons inthe next lower layer of angle irons. The orifices in succeeding layersof angle irons should be similarly proportioned so as to create apressure drop due to the gas flow therethrough which will balance thatthrough the solid column between layers. Since as the gas worksdownwardly, the amount of gas flowing through the orifices graduallyaccumulates and becomes greater and since the amount of gas flowingthrough the column at corresponding levels gradually decreases, the sizeof the orifices 6| in successive downward layers must graduallyincrease. The increase in orifice size is of course limited to thatmaximum size which will still be covered by the base of the anglethereabove. In some cases, by the time the lowermost rows of angle ironsis reached, the orifice size required is greater than the maximumallowable. In order to provide the proper pressure drop balance in suchcases, vertical skirts are provided along the base of the angle irons inthese lowermost layers in order to increase the height of column andthereby increase the pressure drop due to gas flow through the solidcolumn between these layers. In this manner the desired pressure dropbalance may be obtained with a much smaller increase in orifice size inthe lowermost layers of angle irons than wouldotherwise be required. Insome cases with such construction two successive layers having the sameorifice size but different heights may occur. While in general it hasbeen found desirable to provide vertical skirts on the two lowermostlayers of angle irons, skirts may be provided on more than the twolowermost layers of angle irons if desired and even on certain of theintermediately positioned layers of angle irons. It will beunderstandable from the above that while in general, the size of theorifices increase to some extent with each successive layer of angleirons in a downward direction, on some occasions the increase in orificesize may occur only in groups of layers rather than for each successivelayer. For example, in a given application the orifice diametersbeginning with the top layer and working down might be 0.0, 0.4", 0.5"0.6" 0.7" 0.7", 0.8", 0.8", 0.9" 1.0" and so on. It should be understoodthat the expressions in stepwise fashion or "stepwise" are employed inthe claims in the broad sense as covering both a change in orifice sizeor in flow restriction for every successive layer of angle irons and ascovering a change in orifice size or in flow restriction for groups oflayers of angle irons with change in position of the layer in a downwarddirection as described hereinabove.

The exact dimensions and the number of layers of the baflie structuredescribed hereinabove is dependent upon the particular hydrocarbonreaction, reactant rate, contact material and pressure and temperatureconditions involved of the particular application to which the inventionis applied. Moreover the number of layers of angle irons is to someextent dependent upon the dimensions and spacing of the angle ironsemployed. In general, angle irons measuring from about one inch to sixinches across the base may be employed. Preferably the angle ironsshould measure between two to four inches across the base. The sides ofthe angle irons should form a slope with the horizontal of at leastabout 40 and preferably of the order of 60 or greater. The angle ironsshould be so spaced in each layer as to leave a passage for contactmaterial fiow therebetween measuring at least about five times andpreferably ten times as wide as the largest particle of the contactmaterial. The number of layers of angle irons should be suflicient toprovide a-total gas-solid disengaging-area which will limit the linearvelocity of the gas at the disengaging surfaces below that which willboil or substantially entrain the solidpartlcles. The gas velocity whichwill entrain and boil solid particles may be determined by calculationfrom published equations and data or it may be determined by simpleroutine experiments using the particular contact material and gas thatare involved in the process application under consideration. In generalit has been found for catalytic cracking conversion operations that atleast about 4 layers of angle irons should be used.

The rate of decrease in orifice size from layer to layer of angle ironsis dependent upon the particular angle iron size and spacing and uponthe particular contact material and upon the number of layers of angleirons involved.

The number of layers of angle irons and the. 30 proper sizing of theorifices to be employed may be determined in the manner now to bedescribed.

Once having settled upon the total rate of flow of gaseous hydrocarbonproducts and upon the diameter of the conversion vessel for a specificapplication, then the amount of disengaging surface area required may becalculated in the manner described hereinabove. The amount ofdisengaging surface provided by each angle iron may be determined bymultiplying the length of the two converging lines drawn downwardly fromopposite sides of the base of the angle iron at an angle of about 30degrees by the length of the angle iron. Then having selected a suitableangle iron spacing, the total number of layers of the angle irons toprovide the required disengaging area may be easily calculated. Thensince an equal amount of gas is to be collected under each layer ofangle irons the total amount of gas Q to be collected per unit of timeunder any layer of angle irons may be readily determined by dividing thetotal rate of gaseous reactant withdrawal by the number of layers ofangle irons. The rate of gas flow through the column or through thepassage provided by the angle irons at any level is then fixed. Forexample, if there are twelve layers of angles, the quantity/of gasflowing through the orifices in the fifth layer from the top is 4Q andthe quantity flowing through the solid column at the same level must be8Q. The next step is to determine the pressure drop due to gas flowthrough the column between each set of two layers of angle irons. Thispressure dropmay be approximately calculated by known methods and on thebasis of published data and equations. Preferably it may be determinedexperimentally in a small model employing closed angle irons of-the samesize and spacing of those to be employed in the conversion vessel. InFigure 6 there is shown graphically the data obtained experimentally insuch a small model employing angle irons measuring 2 across the base and1.97" in height spaced side by side in each layer on 2%" centers. InFigure 6 the abscissa represents the pressure drop for various gas ratesthrough the same model containing a bed of the contact material but notcontaining any angle irons, and the ordinate represents, for the samecorresponding gas rates, the ratio of the experimentally determinedpressure drop through the bed containing the layers of closed angleirons to the pressure drop for the same gas rate through the angle freebed. The orifices in the angle irons were closed in the experiment toinsure passage of all gas charged through the bed. InFigure 6', twocurves are given, one for spherical gel type catalyst having an averagediameter of about 0.10 inch and the other for pelletted catalyst havingan average diameter of about 0.10 inch. Having calculated the pressuredrop due to gas fiow through the bed between successive layers of angleirons the orifice size for the angle irons in any given layer to balancethe corresponding pressure drop in the contact material bed may becalculated by meansof the simple orifice equation:

-i A CKIZQH where His the pressure drop in the bed across the angle ironin feet of gas flowing, Q is the quantity of gas flowing through theorifice in cubic feet per second, g is the acceleration due togravity=32.2 feet per second, per second A is the area of the orifice insquare feet and C is the orifice coeillcient. The'value of C should bedetermined experimentally. A value of 0.78 for C has been foundsatisfactory for the chimneytype orifices.

As an example of the application of the above calculations, in a processinvolving disengagement of a gaseous hydrocarbon product of aboutmolecular weight at a temperature of 875 F. and pressure of 5#/in. Gaugefrom a particle form catalyst of 45 lbs. per cu. ft. density and 0.12inch average diameter, it was determined that the linear rate of gasflow at the disengaging surfaces to avoid entrainment and boiling of thesolids should be about 2 feet per second maximum. The angle ironarrangement described in connection with Figure 6 was employed. On thebasis of this arrangement it was found that a gas disengaging rate ofabout cubic feet per minute per square foot of vessel cross-sectionalarea was possible. It was calculated that 12'layers of angle irons wouldprovide sufllcient disengaging surface for the total gas flow. Theorifice diameter in inches for successive layers of angle ironsbeginning with the top layer were calculated to be as follows: no portsin top layer, 0.268", 0.395", 0.505", 0.605", 0.710", 0.824", 0.943",1.078", 1.250", 1.250", 1.625. The angle irons in the two lowermostlayers were provided with a skirt measuring inch in height along theirbases.

It has been found that in general for hydro carbon conversionoperations, the total horizontal cross-sectional area of the orifices inthe lowermost layer of angle irons should be at least 2 times andpreferably from 2 to 50 times that of the orifices in the uppermostlayer of angle irons which contain orifices.

The method and apparatus of this invention may be employed in a widevariety of processes involving contact of gas with a column ofparticleform solid material. The invention is particularly applicable tocatalytic processes for the cracking conversion of liquid or vaporoushydrocarbon charges or both. In general such hydrocarbon conversionoperations are conducted under temperatures within the range about 800F. to

- i100 l t, the higher temperatures being employed 600 F.-900 F. and allor part of the heat required for the conversion may be carried into theconversion zone in the catalyst.

It should be understood that the specific examples of apparatusdimensions and of operating conditions and the examples of applicationof this invention given he'reinabove are intended as illustrative andshould not be construed as limiting the scope of this invention exceptas it may be limited by the following claims.

I claim:

1. A method for conversion of fluid hydrocarbons in the presence of aparticle-form contact mass material which comprises: passing saidparticle-form contact material at suitable temperatures for saidconversion downwardly through a confined conversion zone as asubstantially compact column of downwardly gravitating solid particles,introducing a fluid hydrocarbon charge into said conversion zone andpassing it downwardly within said column to effect conversion of saidhydrocarbon charge to gaseous hydrocarbon products, baiiling the solidparticle flow in the lower portion of said column to form a continuoustortuous solid-free passage for gas-flow through a vertical section ofsaid column, said passage being in free gas-flow communication with saidcolumn at a plurality of gas-solid disengaging surfaces at a series ofvertical levels within the lower section of said column, collecting saidgaseous hydrocarbon products from said column into said passage forgas-flow at all of said disengaging surfaces at said series of versaidcolumn at a series of vertically spaced levels, collecting said gaseoushydrocarbon products from said column into said passages at all of saidseries of vertically spaced levels, causing the gas collected at anylevel in said passages to flow downwardly to Join gas'collected at lowerlevels in said passages, subjecting the downward gasflow in saidpassagesto a stepwise decrease in restriction in a downward direction so as toinsure the collecting of gas into said passages from said column at asubstantially uniform rate at all of said vertically spaced levels andwithdrawing from said conversion zone at a level near the lowerextremities of said passages as at least one con- I flned stream thecombined gas collected in said passages from all of said levels.

3. A method for conversion of fluid hydrocarbons in the presence of aparticle-form contact mass material which comprises: passing saidparticle-form contact material at suitable temperatures for saidconversion downwardly through a confined conversion zone as asubstantially compact column of downwardly gravitating solid particles,introducing a fluid hydrocarbon charge into said conversion zone andpassing it downwardly within said column to ef- -fect conversion of saidhydrocarbon charge to spaced levels, causing the gas collected at anytical levels, causing the gas collected into said passage at any levelto flow downwardly to join the gas streams collected at lower levels,subjecting said gas flowing downwardly in said passage for gas-flow to astepwise decrease in flow restriction as it moves downwardly throughsaid series of vertical levels so as to provide substantially uniformdisengagement of gas from said column at all of said disengagingsurfaces at said series of vertical levels, and withdrawing the combinedstream of gas from all of said disengaging surfaces from said conversionzone.

2. A method for conversion of fluid hydrocarbons in the presence of aparticle-form contact mass material which comprises: passing saidparticle-form-contact material at suitable temperatures for saidconversion downwardly through a confined conversion zone as asubstantially compact column of downwardly gravitating solid particles,introducing a fluid hydrocarbon charge into said conversion zone andpassing it downwardly within said column to effect conversion o f saidhydrocarbon charge to gaseous hydrocarbon products, baiiling the solidparticle flow in the lower portion of said column to form a plurality ofsubstantially continuous, tortuous particle-free passages for gas-flowthrough a vertical portion of said column near its lower end, saidpassages permitting gas entrance thereinto from level to flow in ageneral downward direction in said tortuous passages to Join gascollected at other levels. eflecting a stepwise reduction in theresistance to gas-flow through said passages such as to cause a stepwisedecrease in the pressure drop due to gas-flow between any of said levelsin a downward direction, and withdrawing the combined gas collected fromall of said levels from the lower extremities of said passages as atleast one confined stream.

4. A method for conversion of fluid hydrocarbons in the presence of aparticle-form solid contact material comprising: maintaining asubstantially compact column of downwardly moving particle-form contactmaterial within a confined conversion zone, replenishing said column atits upper end with fresh contact material at a suitable conversiontemperature, withdrawingused contact material from the lower end of said:column, introducing a heated fluid hydrocarbon charge into the uppersection of said conversion zone and passing it downwardly within saidcolumn to effect its conversion to gaseous hydrocarbon products,baflling the solid flow in the lower section of said column at aplurality of levels to form a plurality of spaced gas collecting zonesfrom which direct solid flow is excluded at a series of vertical levelswithin the lower section of said column, collecting said gaseousproducts from said column in said gas collecting zones at all of saidlevels, passing the gas collected in said collecting zones at any leveldownwardly as confined solid excluded streams to the collecting zonesnext below so as to accomplish the gradual :combining of gas collectedat said series of levels, subjecting the gas flowing downwardly betweencollecting zones to flow restriction which decreases in stepwise fashionfrom level to level of collecting zones in a downward direction in sucha manner as to accomplish substantially uniform collection of gas fromsaid column at all of said levels and withdrawing the combined gas asconfined streams from the lowermost collecting zones. X

5. An apparatus for conversion of fluid hydrocarbons in the presence ofa moving mass of particle-form contact material which apparatuscomprises: a substantially upright conversion Vessel, means to introducecontact material to the upper section thereof, means to withdraw contactmaterial from the lower section thereof, means to introduce a fluidhydrocarbon charge into the upper section of said vessel, baflie meanswithin a lower portion of said vessel, said bailie means comprisinglayers of inverted troughs, the uppermost layer being positioned withinthe lower section of said vessel, the troughs in each layer being spacedapart and extending horizontally across said vessel in a directiontransverse to those in the adjoining layers, each of said troughs,excepting those in the top layer, having a series of orifices along itsroof, said orifices being so located that in any trough each orifice iscovered by a trough in the layer above, the size of the orifices in thetroughs in said layers increasing in stepwise fashion with the positionof the trough in a downward direction, and means to withdraw gas fromunder only the lowermost layer of troughs to a location outside of saidvessel.

6. An apparatus for conversion of fluid hydrocarbons in the presence ofa moving mass of particle-form contact material which apparatuscomprises: a substantially upright conversion vessel, means to introducecontact material to the upper section thereof, means to withdraw contactmaterial from the lower section thereof, means to introduce a fluidhydrocarbon charge into the upper section of said vessel, baflle meanswithin only a lower portion of said vessel, said bafiie means comprisingcriss-crossed layers of inverted troughs, the troughs in each layerbeing spaced apart and extending horizontally across said vessel in adirection transverse to those in the adjoining layers and the uppermostlayer being positioned at a level within the lower section of saidvessel, a series of orifices along the troughs in each layer exceptingthe uppermost layer and said orifices being so located that in anytrough they will be covered by troughs in the layer next above, saidorifices increasing stepwise in size with downward position of thelayers of troughs and the total horizontal crosssectional area of theorifices in the lowermost row of said troughs being within the range of2 to 50 times that provided by the orifices in the row of troughs nextbelow the uppermost layer ahd means to withdraw gas from only thelowermost layer of troughs to a location outside of said vessel.

7. An apparatus for conversion of fluid hydrocarbons in the presence ofa moving mass of particle-form contact material which apparatuscomprises: a substantially upright conversion vessel, means to introducecontact material to the upper section thereof, means to withdraw contactmaterial from the lower section thereof, means to introduce a fluidhydrocarbon charge into the upper section of said vessel, baiile meanswithin a lower portion of said vessel, said bafile means comprising atleast 4 superposed layers of criss-cross inverted troughs, the troughsin any given layer being parallel and horizontally spaced apart andextending horizontally across said vessel in a direction transverse totroughs in adjoining layers and the uppermost layer being positioned ata level within the lower section of said vessel, a series of orificesalong the troughs in all layers excepting the uppermost and saidorifices being so located that in any trough they.

will be directly below the closed part of the next above trough crossingthereover, said oriflces being equal in size in the troughs in any givenlayer and increasing in size stepwise for succeeding layers in downwarddirection and said orifices in the lowermost layer of troughs providinga total horizontal cross-sectional area at least equal to 2 times thearea provided in the row of troughs next below the uppermost layer, atleast one inverted trough of substantially greater height than saidfirst named troughs positioned below and communicating with said troughsin said lowermost layer, and conduit means to withdraw gas from saidlast named trough.

8. An apparatus for conversion of fluid hydrocarbons in the presence ofa moving mass of particle-form contact material which apparatuscomprises: a substantially upright conversion vessel, means to introducecontact material to the upper section thereof, means to withdraw contactmaterial from the lower section thereof, means to introduce a fluidhydrocarbon charge into the upper section of said vessel, bafile meanswithin a lower portion of said vessel, said baffle means comprisinglayers of inverted troughs, the troughs in each layer being spaced apartand extending horizontally across said vessel in a direction transverseto those in the adjoining layers and the uppermost layer beingpositioned at a level within the'lower section of said vessel, each ofsaid troughs, except those in the top layer, having a series of orificesalong its roof, said ori ces being so located that in any trough eachori ce is covered by a trough in the layer above, the size of theorifices in the troughs in said layers increasing in stepwise fashionwith the position of the trough in a downward direction, a row of spacedinverted troughs of substantially reater height and Width thansaid,first named troughs positioned within said vessel below thelowermost layer of said first named troughs, and communicating with saidtroughs in said lowermost layer through orifices in the roofs of saidlast named troughs, and duct means to withdraw gas only from under saidlast named troughs.

9. An apparatus for conversion of fluid hydrocarbons in the presence ofa moving mass of particle-form contact material which apparatuscomprises: a substantially upright conversion vessel, means to introducecontact material to the upper section thereof, means to withdraw contactmaterial from the lower section thereof, means to introduce a fluidhydrocarbon charge,

' spaced horizontally and being tranverse those of said orifices in saidlayers of angle irons increasing in size in stepwise fashion forsucceeding layers in downward direction, and members defining a passagefor gas withdrawal from under the angle irons in the lowermost layerthereof to a location outside of said vessel, remaining layers of angleirons communicating with said location outside said vessel only throughthe orifices in said lowermost layer. a

10. An apparatus for conversion of fluid hydrocarbons in the presence ofa moving mass of particle-form contact material which apparatuscomprises: a substantially upright conversion vessel, means to introducecontact material to the upper section thereof, means to withdraw contactmaterial from the lower section thereof, means to introduce a fluidhydrocarbon charge into the upper section of said vessel, baiile meanswithin only a lower portion of said vessel, said baille means comprisingsuperimposed layers of angle irons positioned with their angles openingtheir heels and the angle irons in each succeeding layer having a seriesof orifices along its heel being so located that in any angle iron theywill be directly below the closed part of the next above angle ironcrossing thereover, said orifices in the angle irons of any given layerbeing equal in size and the orifices increasing in size in stepwisefashion for succeeding layers in a downward direction, a plurality ofgable-roofed troughs of substantially larger size than said an'gle ironspositioned'directly below the lowermost layer of angle irons andcommunicating with said angle irons through orifices in their roofs, andduct means communicating with the space under said troughs for gaswithdrawal from said troughs.

11. An apparatus for conversion of fluid hydrocarbons in the presence ofa moving mass of particle-form contact material which apparatuscomprises: a substantially upright conversion vessel, means to introducecontact material to the upper section thereof, means to withdraw contactmaterial from the lower section thereof, means to introduce a fluidhydrocarbon charge into the upper section of said vessel,.bailie meansbeginning and extending downwardly within only a lower section of saidvessel, said baiile means comprising superimposed rows of angle ironspositioned with their angles opening downwardly, the angle irons in eachrow being horizontally spaced apart and extending horizontally acrosssaid vessel in a direction transverse to those in next adjacent rows, aseries of orifices along the heels of all angle irons in all rowsexcepting the uppermost rowthereof so positioned that in any angle ironthe orifices are covered by the angle iron crossing thereover, saidorifices being of increasing size in a stepwise fashion for succeedinglylower rows of angle iron, vertical skirts connected along the bases ofall angle irons in at least the two lowermost rows to increase theheightof the angle iron members, a reaction product withdrawal conduit outsideof said vessel, and passage defining members communicating only theangle irons in the lowermost layer with said withdrawal conduit.

12. An apparatus for conversion of fluid hydrocarbons in the presence ofa moving mass of ,particle-form contact material which apparatuscomprises: a substantially upright conversion l6 s vessel, means tointroduce contact material to the upper section thereof, means towithdraw contact material from the lower section thereof, means tointroduce a'fluid hydrocarbon charge into the upper section of saidvessel, bailie means within a lower portion of said vessel, said baflemeans comprising superimposed rows of angle irons positioned with theirangles opening downward-' ly, the angle irons in each row beinghorizontally spaced apart and extending horizontally across said vesselin a direction transverse to those in next adjacent rows, the uppermostrow of angle irons being positioned at a level within the'lower sectionof said vessel above said contact material withdrawal means, a series oforifices along the heel of all angle irons in all rows excepting theuppermost row thereof so positioned that in any angle iron the orificesare covered by the angle iron crossing thereover, said orifices being ofincreasing size in a stepwise fashion for succeedingly lower rows ofangle irons so that the total horizontal cross-sectional area of theorifices in the lowermost row of angle irons is within the range 2 to 50times the area of the orifices in the row next below the uppermost row,vertical skirts connected along the bases of at least the two lowermostrows of angle irons to increase the height of said rows, an externalconduit for transfer of gaseous products, and passage defining I meanscommunicating only the lowermost row of angle irons with said externalconduit.

13. An apparatus for conversion of fluid hydrocarbons in the presence ofa moving mass of particle-form contact material which apparatuscomprises: a substantially upright conversion vessel, means to introducecontact material to the upper section thereof, means to withdraw contactmaterial from the lower section thereof, means to introduce a fluidhydrocarbon charge into the upper section of said vessel, bafile meanswithin a a lower portion of said vessel, said baiile means comprising atleast 4 superimposed horizontal rows of angle irons positioned withtheir angles opening downwardly, the angle irons in each row beinghorizontally spaced apart and extending horizontally across said vesselin a direction transverse to those in next adjacent rows, the uppermostrow of angle irons being positioned at a level within the lower half ofsaid vessel, a series of orifices along the heels of allangle irons inall rows excepting the uppermost row thereof so positioned that in anyangle iron the orifices are.

below the closed part of the angle iron crossing thereover, saidorifices increasingly substantially progressively and uniformly in sizefor succeed-' ing rows of angle irons in a downward direction and thetotal orifice area in the lowermost row of angle irons being at least 2times that in the row next below the uppermost row of angle irons,vertical skirts connected along the bases of all angle irons in at leastthe two lowermost rows to increase the height of the angle iron members,a header for receiving gaseous products outside of said vessel andmembers communicating only the lowermost row of angle irons with saidheader. 14. A method for conversion of fluid hydrocarbons in thepresence of a particle-form solid contact material comprising:maintaining a substantially compact column of downwardly movingparticle-form contact material within a conflned conversion zone,replenishing said column at its upper end with fresh contact material ata suitable conversion temperature, withdrawing used contact materialfrom the lower end of said column, introducing a heated fluidhydrocarbon 1? charge into the upper section of said conversion zone andpassing it downwardly within said column to effect its conversion togaseous hydrocarbon products, baflling the solid flow in the lowersection of said column at a plurality of levels to form a plurality ofspaced gas collecting zones from which direct solid flow is excluded ata series of vertical levels within the lower section of said column,collecting said gaseous products from said column in said gas collectingzones at all of said levels, passing the gas collected in saidcollecting zones at any level downwardly as confined solid excludedstreams to the collecting zones next below so as to accomplish thegradual combining of gas collected at said series of levels, restrictingthe downward gas flow between each of said vertical series of collectingzones in stepwise decreasing amount with downward position of collectingzones, the amount of any two of said series of levels being such as to18 a cause a pressure drop due to gas flow in said passage substantiaflyequal to that of downward gas flow through the column of contactmaterial between the same two levels, and withdrawing the combinedcollected gaseous products as at least one confined stream from thelowermost collecting zones.

HERBERT K. HOLM.

REFERENCES CITED The following references are of record in the tile ofthis patent:

UNITED STATES PATENTS Number Name Date 469,849 Borgarelli Mar. 1, 18921,587,582 Galloway June 8, 1926 2,331,433 Simpson et a1. Oct. 12, 19432,418,672 Sinclair et a1 Apr. 8, 1947 Evans June 24, 1947

